This invention pertains to a mechanism for transforming bidirectional rotation into rectilinear reciprocation, and more particularly to improvements in such a rotary-to-linear converter mechanism of the type used, for example, in a remotely controlled rearview mirror tilting device on a motor vehicle.
Automotive rearview mirror assemblies have been known which have a built-in, remotely controlled tilting device. Actuated by the driver seated in the vehicle, the tilting device automatically adjusts the angular orientation of the mirror, both vertically and horizontally, in order to give the driver an optimum vision of traffic activity to the rear of the vehicle. The rearview mirror tilting device usually incorporates two motor-driven worm gears associated with rotary-to-linear converter mechanisms for tilting the mirror about vertical and horizontal axes.
As heretofore constructed, each rotary-to-linear converter mechanism (shown in FIG. 1 of the accomanpying drawings) in a rearview mirror tilting device comprises a hollow rotor formed integral with the worm wheel of the worm gearing, and a plunger having a portion slidably extending axially through the rotor while being restrained from relative rotation. The plunger is screw threaded to travel axially in response to the rotation of the rotor. This known type of converter mechanism has some disadvantages. One is the easy intrusion of water, as of rain, into the housing of the tilting device through the gap between the contact surfaces of the hollow rotor and the plunger. Another is high frictional resistance offered to the rotation of the rotor by its bearing means.